news: use more significant section headers
news: use more significant section headers

This is arguably better ReStructured Text usage.
indygreg/python-zstandard,indygreg/python-zstandard,indygreg/python-zstandard,terrelln/python-zstandard,terrelln/python-zstandard,indygreg/python-zstandard,terrelln/python-zstandard,terrelln/python-zstandard